A216529 - OEIS

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A216529

Numbers n such that (10^n-1)/9 is prime and can be written in the form a^2 + 3*b^2.

19, 49081, 109297, 270343 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`The exponent is congruent to 1 mod 3.`
	LINKS	`Table of n, a(n) for n=1..4.` `Samuel S. Wagstaff, Jr. The Cunningham Project`
	PROG	`(PARI) is(n)=my(t=10^n\9); ispseudoprime(t) && #bnfisintnorm(bnfinit(z^2+z+1), t) \\ Charles R Greathouse IV, Jun 13 2017`
	CROSSREFS	`Cf. A004023, A003136.` `Sequence in context: A172762 A203703 A068734 * A145851 A182374 A034207` `Adjacent sequences: A216526 A216527 A216528 * A216530 A216531 A216532`
	KEYWORD	`nonn`
	AUTHOR	`V. Raman, Sep 08 2012`
	STATUS	`approved`

Last modified April 16 17:01 EDT 2021. Contains 343050 sequences. (Running on oeis4.)